Even at the best companies, the quality of the job description leaves a lot to be desired. Six of the companies in Glassdoor's Top 10 Employers list just get the job done, two stand out, and two are in a deplorable state.
The main fault with most job descriptions is that they are too big and general. The coolest thing is when the job description is closely tied to the company's mission and employer value proposition, yet written in plain language.